Blower



Dec. 15, 1942.

E. A. STALKER BLOWER 2 Sheets-Sheet 1 Filed Jan. 5, 1940 lNVENTOR Dec. 15, 1942. E. A. STALKER BLOWER Filed Jan.

2 Sheets-Sheet 2 Patented Dec. 15, 1942 UNITED STATES PATENT OFFICE Edward A. Stalker, Ann Arbor, Mich. Application January 5, 1940, Serial N0. 312,522

12 Claims. (or. 230-130) 2 and the impellers 3, 4 and 5.. The inner wan 6 of the conduit in formed by it and the casing My invention relates to pumps and particularly to centrifugal blowers. It has for its objects, first to provide an improved means to compel the flow to follow the impeller and guide vanes and other curved surfaces within the blower, second to provide an improved blowing means thatis substantially self contained.

I attain these objects by the means illustrated in the accompanying drawings in which- Figure 1 is an axial section through a centrifugal blower of the preferred form;

Figure 2 is a section along line 2-2 in Figure 1;

Figure 3 is an axial section through a centrifugal blower employing suction in its curved surface; and

Figure 4 is a section along line 44 in Figure 3.

Because of the sharp bend in the conduit between two stages of a centrifugal blower the flow leaves the surface of smaller radius and becomes turbulent. This represents a great loss of power.

The same kind of loss occurs on the back of the impeller blades and the guide vanes for certain ratios between the rate of rotation of the blades and the rate of flow through them because then the fluid attacks the blades orvanes at too great an angle.

In my Patent No. 2,084,463, granted June 22, 1937, I disclosed means to preclude the formation of the turbulence. The present invention describes an improved means. f

Briefly, compressed air is taken from the later stage and fed back to the earlier stage to provide a jet through suitable slots in the blower walls and blades.

This invention diifers. from the older one chiefly in the means employed to remove the boundary layer. when it is removed by blowing the fluid for this purpose is obtained from a later stage, preferably from the third or a still later stage of the compressor. When it is removed by suction, the means of suction is exter- 118.1 to the machine and a conduit leads to the structure containing the suction slots. and the abstracted fluid is returned to the machine.

In both of thesecases the use of a greater pressure than that obtainable by the device in i the patent cited is very beneficial. Hence in the 1 case of blowing the fluid should be derived from a later stage of compression than the first--and in the case of suction an external pump should i be used.

i Referring particularly to the. figures, the blow- [eris I inFlguresl and2,'composed ofthe casing 2 is perforated with a plurality of slots 1 directed downstream of the flow and preferably extending around a major portion of the periphery of 'the inner wall and about the shaft 8. The conduits between each stage should have such slots.

Fluid is supplied to these slots by the conduits Band l0 which have access at the end H to the compressed fluid in the last stage of the blower.

When the blower is in operation fluid flows from the last stage where the pressure is high to the slots I which direct the issuing jets along the. inner surface of the conduit and prevent the formation of turbulence. None of the energy of theair is lost since the issuing jets are contained pressed fluid through the holes IQ for discharge from the slots 20. I These jets also enable the blower to operate efliciently over a greater range of output. I

In Figure 3 is shown the application of suction to the inner walls 6b. Small openings la. serve for inducting fluid into the compartment [5a from which it is withdrawn by the conduit'fia.

The removal of the layer'of fluid retarded by friction brings new fluid of higher velocity into contact with the walls 6 and the high energy flow is able to follow the curved surface. Thus the turbulence is eliminated and the efficiency improved.

The conduit 9a is connected tothe pump 2| which discharges into the exit tube 22 of the blower I. Thus no fliiid is lost.

The blades 3 and t can receive fluid for discharge from the bladesiots It by the openings I4 which register with the opening H which communicates with the compartment lib and is served by the conduit 9b through the wall 6b. Conduit 91) leads to the last stage of the compressor. In the last stage the-blade slots l6 of blades 5 are served with fluid fromthe opening 23 via the-passage 23a. i

The guide vanes are It and have the suction.

wall between blades to emit a Jet directed radially outward to eliminate turbulence which would form at the juncture of the blade and the im peller disk supporting the blades.

While I have illustrated specific forms of the invention it is to be understood that I do not limit myself to these exact forms but intend to claim my invention broadly.

I claim:

1. In combination, a rotatable impeller having a hollow blade, a casing to house the impeller and conduct its fluid flow, said casing including an air chamber having an annular opening therein, said blade having a slot in its surface in communication withthe hollow interior and an opening registering with said annular opening, and means in communication with said chamber to induce a flow through said blade slot.

2. In combination a plurality of rotatable impellers for inducing a main fluid flow, a casing to house them and conduct the fluid flow between them, said casing having passage walls with curved surfaces between successive imthem, said casing having interior curved surfaces between successive impellers and adapted to provide a slot therein in the vicinity of its curved portion with slot walls formed to direct the slot flow downstream of the main flow substantially along said curved surface, and a conduit communicating with the interior of the casing on thedownstream side of a downstream impeller and with the interior on theupstream side of an impeller through said slot so as to provide a flow therethrough whereby to induce the main flow to follow said curved surface, said conduit crossing the said main flow in the casing between impellers.

6. In combination to form a compressor, a plurality of rotatable impellers, a casing for the conduction of a main fluid flow between them and having a curved wall between successive impellers, said wall being bathed by the main pellers, a said wall being adapted to provide a slot whose side walls direct the slot flow downstream substantially along the said curved surface to induce the said main flow to follow said surface, and a conduit communicating between the interior of the said casing on the discharge side of one impeller and the said slot in the curved wall on the discharge side of another impeller to provide the flow through said slot, said conduit having a length substantially greater than its inner diameter.

3. In combination a plurality of rotatable impellers for inducing a main fluid flow, a casing to house them and conduct the fluid flow between them, said casing having passage walls with curved surfacesbetween successive impellers, a said wall being adapted to provide a slot whose side walls direct the slot flow downstream substantially along the said curved surface to induce the said main flow to follow said surface, and a conduit communicating between the interior of the said casing on the discharge side of one impeller and the said slot in the curved wall on the discharge side of another impeller to provide the flow through said slot, said slot extending transversely to the main flow along a major portion of the casing periphery.

4. In combination, a plurality of rotatable impellers for inducing a main fluid flow, a casing to house them and conduct the flow between them, said casing having interior curved surfaces between successive impellers and adapted to provide a slot therein in the vicinity of its curved portion, the walls of said slot being formed to direct the slot flow downstream of the main flow substantially along said curved surface, and a conduit communicating with the interior of the casing on the downstream side of a downstream impeller and with the interior on the downstream side of an upstream impeller through said slot so as to provide a flow therethrough to induce the main flow to follow said curved surface, said slot extending transversely to the main flow along a major portion of the casing periphery.

5. In combination, a plurality of rotatable impellers for inducing a main fluid flow, a,casing to house them andcofiduct the flow bbtween.

flow and producing a boundary layer of retarded fluid thereon, said wall having in the vicinity of its curved portion a slot leading out of the casing interior, a power driven suction means, and a conduit communicating between said suction means and said slot to withdraw the boundary layer therethrough, said conduit crossing the main flow in the casing between impellers, said slot extending transversely to the main flow along a major portion of the casing periphery.

7. In a compressor, in combination, a plurality of rotatable impellers, a casing to house them and conduct a main fluid flow between them, a hollow guide vane supported in the-flow and having'a slot in its surface in communication with its interior, said vane being adapted to alter the main flow direction, a conduit in communication with the casing interior on the downstream side of an impeller downstream from said vane and withthe interiorof said vane, said conduit supplying a high pressure fluid jet from said slot to induce the main flow to follow the surface of said vane; said conduit having a length substantially greater than its inner diameter.

8. In combination in a compressor, a plurality of impellers disposed along the direction of the main flow to provide an upstream impeller and a downstream'impeller, a casing to house them and conduct the main fluid flow through them, a said upstream impeller having a blade with a slot in its surface in communication with its hollow interior, and a. conduit communicating with the main fluid flow on the downstream side of a said downstream impeller where the fluid pressure is higher than behind the upstream impeller and with the interior of said blade to conduct fluid to said blade for discharge therefrom into the main flow to induce the main flow to follow the curved exterior surface of the blade.

9. In combination in a centrifugal compressor, a plurality of impellers, a casing to house them and conduct the main fluid flow through them, said impellers being disposed along the direction of the main flow to provide an upstream impeller and a downstream impeller, a said upstream impeller having a blade adapted to direct the flow radially outward, said blade having a slot in its surface in communication with its hollow interior, and a conduit communicating with the interior of said casing on the downstream side of a said downstream impeller and with the interior of said blade to conduct fluid to it for discharge therefrom into the main flow to induce the main crease the energy of the boundary layer on the surface of said casing adjacent said upstream impeller.

,casing for housing said impellers and for conducting the fluid flow to said impellers successively to provide a progressively increasing pressure in said fluid flow, means including the wall oi a portion of said casing into which an upstream impeller discharges forming a fluid chamber adjacent said upstream impeller, said 1 wall having a slot therein establishing communication between the interior of said casing adjacent said upstream impeller and said chamber. and a conduit communicating with. a zone of increased pressure of said fluid on the downstream side otsaid upstream impeller, said con-' duit' also communicating with said fluid chamber for supplying fluid thereto under said increased pressure for discharge through said slot to in- 11. The combination or claim 10 in which said impeller-shave hollow blades provided with slots,

and means also communicating with said chamber for supplying pressure fluid therefrom to said blade slots. c

12. In combination a plurality of rotatable impellers for inducing a main fluid flow, a casing to'house them and condut the fluid flow between them, said casing having passage walls with curved surfaces between successiveimpellers, a

said wall being adapted to provide a slot whose side walls direct the slot flow downstream substantially along the said curved surface'to induce the said main flow to follow said surface, and a conduit communicating between the interior of the-said casing on the discharge side '01 a downstream impeller and the said slot in I the curved wall on the discharge side of an upstream impeller to provide the flow through said slot.

, EDWARD A. STALKER. 

